Robbia had been bred to the trade of a goldsmith--in those days a trade of great distinction and opulence--but his artistic tastes could not be controlled, and he abandoned it to become a sculptor. A man of a singularly enthusiastic and ardent nature, he applied himself arduously to his new work. He worked all day with his chisel, and sat up, even through the night, to study. "Often," says Vasari, "when his feet were frozen with cold in the night time, he kept them in a basket of shavings to warm them, that he might not be compelled to discontinue his drawings." Such devotion could hardly fail to secure success. Luca was recognised as one of the first sculptors of the day, and executed a number of great works in bronze and marble. On the conclusion of some important commissions, he was struck with the disproportion between the payment he received and the time and labour he had expended; and, abandoning marble and bronze, resolved to work in clay. Before he could do that, however, it was necessary to discover some means of rendering durable the works which he executed in that material. Applying himself to the task with characteristic zeal and perseverance, he at length succeeded in discovering a mode of protecting such productions from the injuries of time, by means of a glaze or enamel, which conferred not only an almost eternal durability, but additional beauty on his works in terra cotta. At first this enamel was of a pure white, but he afterwards added the further invention of colouring it. The fame of these productions spread over Europe, and Luca found abundant and profitable employment during the rest of his days, the work being carried on, after his death, by brothers and descendants. II.--BERNARD PALISSY. The next great master in the art was Bernard Palissy,--a man distinguished not only for his artistic genius, but for his philosophical attainments, his noble, manly character, and zealous piety. Born of poor parents about the beginning of the sixteenth century, Bernard Palissy was taken as apprentice by a land-surveyor, who had been much struck with the boy's quickness and ingenuity. Land-surveying, of course, involved some knowledge of drawing; and thus a taste for painting was developed. From drawing lines and diagrams he went on to copy from the great masters. As this new talent became known he obtained employment in painting designs on glass. He received commissions in various parts of the country, and in his travels employed his mind in the study of natural objects. He examined the character of the soils and minerals upon his route, and the better to grapple with the subject, devoted his attention to chemistry. At length he settled and married at Staines, and for a time lived thriftily as a painter.